This invention relates to improvements in the structure of well cars, and in particular to a resistance to lateral loads through an improved floor design.
Railway well cars may be considered as upwardly opening U-shaped channels of a chosen length, simply supported on a pair of railcar trucks. Although single unit well cars are still common, there has been a trend in recent years toward articulated, multi-unit railcars which permit a relatively larger load to be carried on fewer railcar trucks.
Contemporary well cars may carry a number of alternative loads made up of containers in International Standards Association (ISO) sizes or domestic sizes, and of highway trailers. The ISO containers are 8xe2x80x2-0xe2x80x3 wide, 8xe2x80x2-6xe2x80x3 high, and come in a 20xe2x80x2-0xe2x80x3 length weighing up to 52,900 lbs., or a 40xe2x80x2-0xe2x80x3 length weighing up to 67,200 lbs. Domestic containers are 8xe2x80x2-6xe2x80x3 wide and 9xe2x80x2-6xe2x80x3 high. Their standard lengths are 45xe2x80x2, 48xe2x80x2 and 53xe2x80x2. All domestic containers have a maximum weight of 67,200 lbs. Recently 28xe2x80x2 long domestic containers have been introduced in North America. They are generally used for courier services which have lower lading densities. The 28xe2x80x2 containers have a maximum weight of 35,000 lbs.
Two common sizes of highway trailers are, first, the 28xe2x80x2 pup trailer weighing up to 40,000 lbs., and second, the 45xe2x80x2 to 53xe2x80x2 trailer weighing up to 60, 000 for a two axle trailer and up to 90,000 lbs. for a three axle trailer. It is advantageous to provide well cars with hitches at both ends. This permits either a single 53xe2x80x2 three axle trailer to be loaded in either direction, or two back-to-back 28xe2x80x2 pup trailers to be loaded.
The wheels of a trailer can rest in the well, with the front, or nose of the trailer overhanging the car end structure at one end or the other of well car unit. A second trailer may rest in the well facing in the opposite direction. Alternatively, shipping containers, typically of 20 ft., 28 ft, or 40 ft lengths may be placed in the well, with other shipping containers stacked on top. Further, well cars may carry mixed loads of containers and trailers.
Whichever the case may be, a well car is required to withstand three kinds of loads. First, it must withstand longitudinal draft and buff loads inherent in pulling or pushing a train, particularly those loads that occur during slack run-ins and run-outs on downgrades and upgrades. Other variations of the longitudinal load are the 1,600,000 lbs. squeeze load and the 1,250,000 lbs. single ended impact load. Second, the well car must support a vertical load due to the trailers or shipping containers it carries. Third, it must be able to withstand lateral loading as the well car travels along curves and switch turn-offs. It is important to carry these structural loads while at the same time reducing the weight of the railcars themselves, first to permit a greater weight of freight to be carried within the overall maximum car and load weight limit, and second to reduce the amount of deadweight that must be pulled when the car is empty. Third, a lighter car may be less costly to build.
The U-shaped section of the car is generally made up of a pair of spaced apart left and right hand side beams, and structure between the side beams to support whatever load is placed in the well, and to carry shear between the sills under lateral loading conditions.
In earlier types of well car the side sills tended to be made in the form of a single, large, beam. While simple in concept, they were often wasteful, having an unnecessary amount of material in locations where stress may have been low. It is advantageous to have a sill in the form of a hollow section, of relatively thin walls, and to provide local reinforcement where required. It is also desirable that the hollow section be as manufactured at the mill, whether as tube or roll formed section, if possible, rather than welded. This often yields a saving in effort, may permit the use of a higher yield stress alloy, and may also reduce the number of defects or stress concentrations in the resulting structure. As the wall thickness decreases the prospect of buckling under buff loads and vertical loads increases, and measures to deter buckling would be advantageous. It would also be advantageous to provide protection for the sills to discourage damage to the sills due to clumsy loading of trailers or containers.
In the past, one method of dealing with areas of higher flange stresses in the side construction was to use a member of greater weight. As the thickness of structural members is reduced it would be advantageous to transfer loads from the railcar trucks to the bolsters, and thence to the side sills, more smoothly to discourage or reduce stress concentrations. One way to do this is to increase the depth of section at the bolster, with a consequent increase in height of the end decking.
The present invention provides, in a first aspect, a transverse force resolver for a railcar having a pair of longitudinally extending side sills, comprising a structure having one longitudinal force transfer interface for transferring force to one side sill and another longitudinal force transfer interface for transferring force to the other side sill. A transverse force transfer interface is provided for transmitting a transverse force to one of the side sills. The transverse force transfer interface is offset from the one longitudinal force connection by a longitudinal moment arm distance. The transverse force transfer interface has longitudinal slip.
Additionally, that aspect of the invention may be such that the longitudinal force connections are structurally equivalent to a pin jointed connections. Also, additionally, in that first aspect of the invention the longitudinal connections can be for location at substantially the same longitudinal location of the railcar. In yet another additional feature of that aspect of the invention the force resolver can comprise another transverse force connection for transmitting a force to the other side sill, and the other transverse force connection is offset from the longitudinal force connection by another longitudinal moment arm distance.
In a different additional feature of that aspect of the invention, the force resolver can include a cross beam and a moment structure mounted thereto. The longitudinal force connections are located at opposite ends of the beam. The moment structure extends away from the beam; and the transverse force connection is mounted to the moment structure.
In yet another additional feature of that aspect of the invention, the force resolver transverse force connection can include an abutment for abutting a reaction member mounted to the side sill. In a still further alternative feature of that aspect of the invention, the force resolver can include abutments for abutting reaction stops for transmitting clockwise and counterclockwise moments to the longitudinal force connections. And, in each case, the force resolver moment structure can be a floor panel of the railcar.
In another aspect of the invention, there is a transverse force resolver for a railcar having a pair of longitudinally extending side sills, comprising a structure having a longitudinal force connection for connection to one of the side sills, and a pair of transverse force transfer interfaces for transmitting transverse forces to the side sills. One of the transverse force transfer interfaces is offset from the longitudinal force connection by a longitudinal moment arm distance; and the transverse force transfer interfaces have longitudinal slip.
In an additional feature of that aspect of the invention, the transverse force resolver is for a railcar having a pair of spaced apart cross beams extending between and connected to the side sills, wherein each of the transverse force connections is mountable to one of the cross beams.
In another aspect of the invention, there is a rail car having a pair of longitudinally extending side sills. A pair of spaced apart cross beams extend between and are connected to the side sills. A pair of force resolvers, as described in the previous aspect of the invention, each have one of the transverse force connection mounted to one of the beams, and the other of the transverse force connections mounted to the other of the beams. One of the force resolvers has its longitudinal force connection connected to one of the side sills and the other of the force resolvers has its the longitudinal force connection connected to the other of the side sills.
In a still further aspect of the invention there is a transverse force resolver for installation between a pair of longitudinally extending side sills of a railcar, comprising a pair of longitudinal force connections, one connected to one of the side sills and the other connected to the other of the side sills. A pair of transverse force transfer interfaces are provided for transmitting transverse forces to the side sills. Each of the transverse force transfer interfaces is offset from the one of the longitudinal force connections by a longitudinal moment arm distance, and each of the transverse force transfer interfaces has longitudinal slip.
In an additional feature of these aspects of the invention the transverse force resolver can have longitudinal force transmitting interfaces chosen from the set of connections consisting of (a) a bolted connection; (b) a pin jointed connection; (c) a welded connection; (d) a rivetted connection; and (e) a sliding connection with transverse slip. Similarly, in an additional feature of these aspects of the invention, the transverse force connections have abutments for transmitting forces to either side of the rail car.
In a further additional feature of any of the above aspects of the invention, the transverse force resolver can include a cross beam having longitudinal force connections at either end thereof and a pair of mounted structures attached to transmit a moment thereto. One of the mounted structures extends longitudinally forwardly and the other extends longitudinally rearwardly therefrom. Each of the mounted structures has one of the transverse force connections mounted thereto. In a yet further additional feature of that additional feature, the transverse force resolver includes a pair of the mounted structures that extend forwardly of the cross beam and a pair of the mounted structures extend rearwardly of the cross beam. Each of the mounted structures have one of the transverse force connections mounted thereto.
In a still further aspect of the invention, there is a floor panel assembly for a railcar having a pair of longitudinally extending side sills, comprising a first cross member extending between and connected to the side sills, and a moment arm structure mounted to the cross member for transmitting a moment thereto. The moment arm extends away from the cross member and has a transverse force transfer interface for transmitting a transverse force to one of the sills. The transverse force transfer interface having longitudinal slip.
In an additional feature of this aspect of the invention, the floor panel assembly can extend substantially perpendicular to the side sills. In another additional feature of this aspect of the invention, the floor panel assembly includes a second moment arm structure. The first moment arm structure extends longitudinally forwardly from the cross member and the second moment arm structure extends rearwardly thereof. The second moment arm structure has a transverse force connection, having longitudinal slip, for transmitting a force to the other side sill.
In yet a still further aspect of the invention, there is a well car comprising a pair of spaced apart, longitudinally extending side sills. A floor cross member extends between and is connected to the side sills. A moment arm structure is connected to the cross member for transmitting a moment thereto. The moment arm having a transverse force transfer interface for transmitting force to one of the side sills, and the transverse force transfer interface has longitudinal slip.
In an additional aspect of that invention, the well car can include a floor cross beam that extend between, and is connected to, the side sills, spaced from the cross member. The transverse force connection is mounted to the cross beam to transmit force to the one side sill through the beam.
In another additional feature of that aspect of the invention, the well car can further comprise another cross beam extending between and connected to the side sills, spaced apart from the one the cross beam. The cross member is located between the cross beams and another moment arm structure connected to the cross member for transmitting a moment thereto. The other moment arm structure has a transverse force connection to the other cross beam, and the other transverse force connection has longitudinal slip.